I have concerns for a friend who is bi polar?

People with mental health problems have to deal with the real world just like everyone else, you can't shield your friend from it although your intentions are good. Just be there for her in the same way you would if any other of your friends who was dumped by someone they felt they were in love with. It's impossible to know how she will react, it depends on her own coping skills and devices. Let her know that you're there for her, and if you can ensure she takes her medication as usual and encourage her to utilise professional support and help if she needs it. That will help her from sinking too low. Hope it all works out.